Desiccating apparatus



'Au .10,1943. H AN REW; 2,326,512

DESICCATING APPARATUS Filed Dec; 28, 1938 4 Sheets-Sheet .l

SEPARATOR .10 /6' AIR PUMP Z9 2 I STERILIZER BLOWER INVENTOR Mater 1. A/VDEEWJ BY W ATTORNEY g- 1943- H. [ANDREWS DESICCATING APPARATUS 4 shets sheet 2 Filed Dec. 28, 1938 mm 7 NM NM \W% D 19% .0 NM :1 BIN \W h m NM 7 1% IN n M mw Ale/2v I. Amazsws ATTORNEY 8 Aug. 10, 1943. H. ANDREWS DESICCATING APPARATUS Filed Dec. 28, 1938 4 Sheets-Sheet 3 .l s N%\ m J7 J7. v RX Q \m\ m w NA R Q g 3 E. o v] w $3 w m y A wfi 2 M H m H. I. ANDREWS DESICCATING APPARATUS Filed Dec. 28, 1938 Aug. 10, 1943.

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ATTORNEY Patented Aug. 10, 1943 UNITED STATES PATENT OFFICE 2,326,512 DESICCATING APPARATUS Harry I. Andrews, South Norwalk, Conn. Application December 28,1938, Serial No. 248,031 13 Claims. (cuss-12) The present invention relates to a new apparatus for desiccating milk and other products, and represents improvements on the disclosure of my United States Patent No. 1,012,578. This application is a continuation in part of my copending application Ser. No. 15,347, filed April 8, 1935 and now issued as Patent 2,143,256.

It is an object of this invention to provide an improved apparatus for desiccating whole or skimmed milk, ice cream mixes and the like to reduce the same to the consistency of condensed milk or to substantially dry flakes or powder.

It is also an object of the invention to provide such an apparatus whereby an improved milk product is produced which is capable, upon addition of water, to form milk that is practically undistinguishable from fresh whole'milk.

' It is a further object of this invention to provide an improved apparatus whereby water may be removed from milk without impairing the nutritive value or taste of the milk.

Generally, the present invention relates to an apparatus for desiccating not milk alone but various other products in a quick economical way, and without loss of important minerals and/or other elements.

In apparatuses employed at the present time to produce dried milk and some other products,

it is desired to free the product from bacteria.

Heretofore it has been customary to provide a step of pasteurization in the dry milk process. However, this pasteurization processvery often results in overheating the milk and in a definite loss or change of flavor in the final product.

- It is an object of the present invention to provide a desiccating apparatus and process, for

ing products. For example, milk from cows within barns and fed from hay in the wintertime does not taste as good and is not assrich in sunshine vitamins as is milk produced out of doors with the fresh grass in .the summertime.

Apparatus usually employed for desiccating milk and other products are most often built upon a spray principle and requirebulky, awkward apparatus and take up much space.

It is an object of the present invention to provide a compact desiccating apparatus which will be capable of alarge production but which will requirebut very little space. 4 Some of the-featurs in connection with this object include the provision of a single housing adapted to dehydrate skimmed and/or whole milk (and to irradiate the product); to aerate, mix and/or dry dehydrated skimmed milk; to

congeal and/or break up the last mixed product;

and/or to. further dehydrate the congealed and/or broken-up product.

It is a further object to provide a highly efficient desiccating apparatus which is easy and economical to construct and which is easy to producing dry milk particularly inwhich the bacteria may be destroyed, and yet have the product regain all of its original flavor and like propv erties when water is added later.

operate.

These and other objects, features, and advantages of this invention will more fully appear 1 housing, taken on lines 2-2 oi Figs'. 1 and 3.

In meeting this object the present invention provides as a step in the dehydrating process, the step of subjecting the producttovery high fre I Fig. 3 is a sectional view taken on line 3-4 of Fig. 2 z

Fig. 4 is a plan View of the right-hand side of t the main housing shown in Fig. 3.

quency oscillations, capable. of destroying baoconstituents of the milk. Thus, the'p'resentdnvention provides'an imteria but having no adverse effects on the other proved condensed or dried milk, or other p. "duct, wherein bacteria-are removed by higli frequency oscillationsi At the present ciation of .improved health and food value of food products having vitamins naturally stored from sunlight. It is an object of the present in.

vention to provide a process capable of irradiate- I 2 time there is a growing appre- Fig. 5 isgassectional view similar to Fig. 3, taken 5- -in Fig. 6, but showing a modifle form of the present invention.

Fig. 6 is a view of the right-hand end of th casing shown in Fig. 5.

Fig. 7 is a fragmentary sectional viewof the aerating drum.

Fig. 8 is a fragmentary detail view showing the construction 'of the screen and perforatedjacket of the aerating drum.

Fig. 91s a sectional viewtaken on the line 9- 9 'ofFig.5.'

parts shown in the accompanying drawings,

which are merely illustrative of the present preferred embodiments, since the invention is capable of other embodiments, and the phraseology employed is for the purpose of description and not of limitation.

Referring to Figs. 1 through 4, there is shown a storage tank H in which the milk l5 may be kept under appropriate conditions of temperature until it is to be treated. This tank is connected with a cream separator l6 by means of pipes l1 and H (which may be provided with valves and metering devices in order to control and measure the flow of milk from the tank). The separated cream is discharged into a tank l3 through a pipe l9 while the skimmed milk is, discharged from-the separator into a suitable sterilizer 210 through a pipe 2|. This sterilizer may comprise an ozonizer as illustrated in my aforesaid patent, or it may take the form of means for subjecting the milk to high frequency electro-osclllations such as is described in U. S. Patent No. 1,863,222.

By thus subjecting the milk to high frequency vibrations it is possible to destroy bacteria or germs and to do this without Overheating. and without destroying the enzymes or life of the milk.

The sterilizer may be located to sterilize only the skimmed milk as shown by dot-and-dash lines 26' in Fig. l, or it may be located before the separator as shown by full lines 26a in the same Fig. 1, in order to sterilize the whole milk.

The sterilizer discharges the skimmed milk into the primary evaporator 22. The evaporator consists of a substantially air-tight main casin 24, including sidewalls 25 and 26, front and rear walls 21 and 28 surmounted by a smaller casing 29 in which an air or vacuum pump 30 is mounted. Apipe 2|, which carries the skimmed milk from the sterilizer, discharges onto an inclined tray 3| which distributes the skimmed milk in a relatively thin film for application to the hot and .cold rolls 32 and 33 respectively mounted in the main casing. The several rolls are mounted for rotary movement and a suitable driving mechanism 34 such as' a, chain and sprocket or intermeshing gears 35 as shown is provided in order to transmit rotary movement .from a motor or event all the rolls could be rotated in the same direction'or in the opposite directions as described above. Regardless of the direction oi. rotation of the rolls, insulating shields 31 may be arranged opposite the ascending sides of the respective rolls to reduce radiation losses.

Each roll of the evaporator has a hollow chamber 38 and is provided internally with means for heating or. cooling the roll. The heated rolls Fig. is a fragmentary sectional view similar 1-4 by passing steam or any heated fluid from a feed pipe 33 to an inlet manifold 40 and outlet manifold 4| and intermediately influencing the inner surface of the rolls. "The cold rolls 33 may be cooled by passing refrigerated brine or other fluid through a main pipe 42 to an inlet manifold 43 and outlet manifold 44 arranged within the roll. v

Now it should be noted that the rolls 32 and 33 are each, as shown in Fig. 3, provided with hubs 45 having suitable bearings in the side walls and support glasstubes 46 so that the heat or cold passing therefrom to the products engaging the 'by the individual valves 48.

roller are not given a metallic taste.

Temperature of the individual hot rollers 32 may be regulated by individual valves 48 so that onemay be hotter or cooler than the other (see Fig. 3) and the individual rollers may be directly interspersed as in my aforesaid patent. Preferably, the improved apparatus of the present; invention, in order to speed up the evaporation or desiccation processes includes groups of three rolls each. The top roll of each group is heated to such a temperature that the outer periphery of the roll is maintained at a temperature of approximately 145 to 150 degrees Fahrenheit. The next roll below is heated so as to obtain a temperature of approximately 135 to 140 degrees Fahrenheit at 'the outer periphery of the roll. Temperature of individual rolls maybe controlled The third roll of each group is cooled so that the temperature at the outer periphery of this roll is preferably 35 to degrees Fahrenheit.

Any desired number of groups of three rolls each may be provided in order to obtain the desired dehydrating action.

Suitable valves 48, and 56 are arranged to control the supply of heat and cold to the respective rolls. Thermometers or pyr'ometers; visual or recording, not shown, are provided to guide the operator in the manipulation of the valves.

At the bottom of the evaporator section 22 a trough 51 is mounted to receive the concentrated milk as it is discharged from the lowermost roll 33. A doctor blade 58 may be provided to scrape the lower roll. A pipe 59 conducts the cream from tank i8 and discharges the same into the trough 51 and is controlled by a valve 15. As shown in Fig. 3 the end 60 of the trough 51 is inclined downwardly to form a discharge end 6|. Arranged below the discharge end 6| is a plurality of trays 62, 63 and 64, each tray being inclined in a direction opposite to that of the tray'immediately above. The mixture of cream and concentrated skimmed milk cascades in a zigzag course down over the several trays.

Adjacent the lowermost tray 64 an air inlet 65' is provided through which air may be admitted and controlled by a valve 66. A blower 61 on the,

frame 63 and actuated by a belt connection 69 to the main driving mechanism 36 is adapted to draw air through a screen 10 and to force it through a line H The valve 66 controls'the extent of flow, and a coil" associated with the line H is adapted to heat the air passed therethrough Under the action of the air pump 30 provided in upper casing 23 air is drawn through the inlet 65 and upwardly over the trays 64, 63, and 62 through the cascading mixture countercurrent to the flow thereof, aerating it and causing addi- Y tional removal of moisture from the same. A may be heated electrically or as shown in Figs. The bl wer the bump 30 alone may force charged through an opening ne II upwardly over the trays length of the roll I4 and end members I8 and'13.

One side member I6 alone or with sealing means is mounted to bear against the roll to prevent leakage of the mixture from the head box. The other side member 11 is adjustably mounted and is so arranged that a space of uniform width exists between the roll and said side member for the discharge of material from the head box. This roll is maintained at a temperature of approxi-- mately 35 degrees Ffby means of a connection 80 with a refrigerant manifold 43 and valve 8|,

and is rotated by the motor 36 as by a belt connection 82 .to a shaft 83, all as shown in Figs. 1, 3 and 4. The mixture is discharged into the head box at one end of the same and flows lengthwise of the roll to such a point that the lateral discharge under the s de of the head box is sufficient to remove the mixture from the head box as rapidly as the mixture is supplied. The side of the head box is maintained at a uniform distance from the roll in order to insure the formation of a film on the roll of uniform thickness. Means may be provided to enable an adjustment of this side in order to vary the thickness of the film v and/ or the capacity of the roll.

A coupling 84 joins the tray 64 and head box 13 together yet permits transverse shifting of the latter, which shifting is effected by a screw 85,

to move the wall I1 relative to the roller 14 and thereby vary the film.

The mixture is congealed to a thin brittle fllm on the roll 14. A doctor blade at is provided to scrape the film from the roll as thin flakes, and discharge the same into a, hopper 81 located above a screw conveyor 88 which is preferably of a length considerably greater than that of the roll I4. The'flakes pass from the hopper 8Iv down into the trough 89 where the screw 88 operates. The screw may be operated by the main drive 36 shown in Fig. l. Rotation of the screw transports the flakes frombeneath the hopper and into the housing 90. During the transportation of the flakesthrough housing 90, a current of air from a side duct 9| of the line II is forced over the flakes to evaporate the remaining removable water-to obtain the desired produ During the earlier stages of the movement of the flakes by the screw, it may be desirable to maintain the flakes at a relatively low temperature. This may be accomplished by arranging coils 02iaround the housing 90 and trough 89. A very simple and practical way' of achieving this result is to add small lumps of solid carbon dioxide 93 ,to the flakes at the inlet end of the screw 88 from a hopper 94 and control 95. The solid carbon 'dioxidelsublimes, refrigerating the newly formed flakes as desired. Furthermore, the gaseous car bon dioxide formed assists in the final dehydra 6 tion of the chips. A current of dry air at normal room temperature, or heated by the coil I2, is

introduced at 'the'd'i'scharge end of the screw. This air passes countercurrent to the flakes in the housing 8 to eflect a very complete dehydration, and passes through the main casing 24. thenceupwardly and out I ."If itis desired-to further break downthe flakes of the openings 28'.

'aftenthey'leave'the housing 90, they may be dis- 80 111150 suitable 'u similarlyf chieved by passihga refrigerant thei'e grinding device, such as shown at G breaking or in Fig. 1'. V

Briefly, the process for desiccating milk would be as follows: Upon obtaining suflicient milk to commence operations, milk is discharged from the reservoir l5 to the cream separator I3. Cream is separated and removed to a suitable tank I8, the skimmed milk being passed through a suitable sterilizer 20.

- In the present preferred form it is flrst passed over a pair of hot rollers 32, thesurface temperature of the first being approximately 145 to 150 degrees F. It is not desirable to heat milk above 140 degrees F. but the milk is in contact with this roll for such a short period of time that the' milk does not reach the temperature of the roll surface. The milk then passes to another heated roll, the surface temperature of which is approximately 135 to 140 degrees F. After passing down this roll, the milk is chilled by the cold roll 33.; This cycle of temperature treatments is repeated one or more times until the desired concentration of skimmed milk is obtained. During 'the said treatment in the primary evaporator,

milk to assist evaporation.

the troughS'I the cream'is remixed with the skimmed milk. This mixture is allowed to,cascade downwardly over the trays 62-64 while passing air through and over the mixture whereby the mixture is further evaporated, the cream and skimmed milk are thoroughly intermixed and aerated. Ifit is desired to convert this concentrated material to a substantially dry flake or powder, the'concentrated material is congealed to a thin hard fllm on the refrigerated roll, the fllm broken up to a flaky material which is further dehydrated by passing the same through a housing 90 where it is subjected to air which is progressively drier as the flakes approach. the pointof discharge.

In Figs. 5 through 9 another modified form of the invention is shown. It includes a modified ported. by the endwalls I32 and I33 are a plu-' rality of vertically spaced, horizontally'extending main rollers I40, MI and I42. Preferably, and as shown, these main rollers are in slightly stag gered relation as are the rollers 32 and 33in the form first described;and, similarly to those rollers, include hollowhubs I43 insertedin suitable bearings I44 in the end walls and which support glass tubes I so that the milk contacting the rollers is not given a metallic taste.

To provide alternate zones of heat andcold within the casing I3 I, the upper and lower rollers I40 and I42 are heated and the intermediate roll.- er vI4I .is chilled. This' mlay be advantageously ated with the hollow hubs I43 which exten 7 through the endwall I33. A return manifold 1 associated with the hollow hubs I43 at the othe end of the rollers I40 and. I42 is provided for con veying the heated. id away, from the rollers The chilling of the inte ediate roller I may air is continuously drawn through and over the evaporator I30 having. a main casing I3I. As

through, as by associating the hollow hub I43 at one end of the roller I4I with a refrigerant inlet conduit I48 and the hollow hub I43 at the other end with an outlet conduit I49.

While only three rollers I40, MI and I42 have been shown it is to be understood that more than three rollers may be utilized and that a pair of hot rollers may be used together as in Figs. 2 and 3, the important factor being that the rollers are arranged so as to provide alternate zones of heat and cold.

Now of importance, there is embodied in this modified form of the invention a milk-receiving tank I50, suitably supported in an opening II in the top wall I49, and preferably having downwardly converging side walls I52 and I53 separated at the lower ends to provide a flow passage I54 for directing the milk onto the heated upper main roller I40. As shown, the lower end of the wall I 52 is in engagement with the roller while the lower end of the other wall I53 is spaced slightly upward of the roller to permit the milk to form in a relatively thin sheet as it flows onto the roller.

To further spread the milk over the roller I40 and to render the sheet more uniform there is preferably provided a calender roller I55 which is spaced from the main roller I40 just sufliciently to permit the passage of a thin sheet of liquid milk therebetween. This calender roller by being heated to a'temperature preferably somewhat in excess of the main roller I40 serves, in addition to spreading the sheet of milk, to give the milk a preliminary heat treatment and thus more quickly raise the temperature of the milk coming from the receiving tank. A suitable electric heating element I56 in the calender roller I55, which, as shown, may comprise hubs I51 and I58 journaled in suitable bearings I59 in the end walls I32 and I33 and supporting a glass tube I60, provides an advantageous means for heating the roller. A suitable electric conduit I6I may be inserted through a bore I62 in the hub I58 to connect the heating element I56 with any inconvenient source of electricity,

Of particular importance there is positioned in the casing below the lower main roller I42 -a rotatable drum I63 so constructed that as the milk leaves the lower heated roller I42 and form in a thin sheet thereon, warm dry air or oxygen is bubbled through the milk from the interior of the drum. This drum I63 comprises a tubular screen I64 of very fine mesh. The screen while permitting air or oxygen from the drum to pass outwardly into the milk, serves to prevent the milk from entering the interior of'the drum. Overlying the screen I64 and rotatable therewith extremity of the slot I68. A doctor blade I connected to the forward pivoted part I10 adjacent the longitudinal edge I16 thereof defining the forward extremity of the slot I68 is yieldingly maintained in scraping engagement with the drum I63 and, in addition to serving as a means for removing milk from the drum, serves to complement the packing rings I12 and packing strip I13 in sealing the drum.

As the milk leaves the lower main roller I42 it is received and supported in the form of a thin sheet on that portion of the rotatable drum which is exposedthrough the slot I68 and is carried,

around by the drum to a point adjacent the forward extremity of the slot. There the doctor blad I15 scrapes the dehydrated milk from the drum.

As shown in Figs. 5 and 9 the drum may be rotatably mounted in bearings I11 in the end walls I32 and I33 of the casing by means of integral hub extensions I18 and H9 on opposed end plugs I80 and I8I respectively which provide the support for the tubular wire screen I64 and jacket I65. In this construction the end plug I80 is formed solid while the end plug I8I and hub extension I19 are formed hollow to provide a passage I82 for warm dry air from a suitable blower I83 to the interior of the drum.

This blower I83, which'as shown is preferably of the rotary type, draws air from any suitable source through an, inlet pipe I84 and forces the same outwardly through an outlet pipe I85 associated with the hub I19. A thermostatically controlled" electric heater I86 may be conveniently placed in the inlet pipe I84 to maintain the air v entering the drum at any desired temperature.

is a tubular jacket I of perforated sheet metal which serves as a guard for the screen.

Fixed to the end walls I32 and I33, as by suitable brackets I66, is a tubular sealing shield I61 formed with a longitudinally extending slot I68 in the upper side thereof, and pwitioned to confine closely therein the rotatable drum I63.

As shown, this sealingshield I6'I comprises a rear part I69 to which the brackets I66 are se- In order that each of the several rollers I55, I40, MI and I42 and the drum I63 may be rotated concurrently there is fixed to the hub I19 of the drum I63 a pulley wheel I81 connected to a pulley wheel I88 on the hub of the lower main roller I 42 by a belt I89. A chain of gears I90 interconnectingthe hubs of the other main rollers I 40 and MI and the calender roller I 55 serves to complete the driving mechanism.

Positioned below the drum I 63 and adjacent the bottom of the casing I3I is a screw conveyer I9l mounted on a shaft I92 extending through the end wall I33. This screw conveyer I9 I, like the screw conveyer 88 in Fig. 3, extends out of the main casing I 3I and into a housing I93 extending laterally from the main casing and from which the dehydrated milk is discharged. Rotation of the conveyer I9I may be achieved ina manner similar to the rotation of the conveyer 88 in Figs. 1 and 2, and through a belt connection I94 between a pulley wheel I95 on the shaft I92 and a pulley wheel I96 on the hub I19 01 the drum, concurrent actuation of the chain of gears I90 may be achieved.

Inthe operation of the modified evaporator I 30 1 milk may be conveyed from any suitable source,

as from a storage tank, such as shown in Fig. l, to the receiving tank I 50. There the milk is preferably sterilized by bubbling ozone therethrough from a perforated cylinder I91 supported by the cured, anda forward part I10 pivotally secured."

to the rear part by sprin hinges I1 I.

To definitely limit the escape of air or oxygen from the rotatable drum to the limited area defined by the slot I68, suitable packing rings I12 are secured to the shield I61 at oppositeends thereof, and a packing strip I13 is secured to the shield to extend longitudinally thereof adjacent the edge I14 of the rear part I69 defining the rear end walls I32 and I33 and which may be connected, as by a conduit I 98, to any suitable'source of ozone under pressure.

By gravity, the milk then flows from the receiving tank I50 to the upper heated roller I40 which in the modified evaporator I 30 is preferably maintained at a temperature of from degrees to degrees F. The calender roller I55, which is preferably maintained at a temperature of about I 2,320,512 140 degrees F.. cooperates with the main roller I40 to form the milkin a thin even sheet and aids the roller I40 in initially raising the temperature of the milk.

From the roller I40 the milk drops to the chilled roller I4I which is preferably maintained at a temperature of from 35 to 40 degrees F., and from thence the milk falls onto the lower heated roller I42 which, like the upper roller I40, is preferably maintained at a temperature of from 115 to 120 degrees F.

During the passage of the milk downwardly over the several rollers I40, MI and I42 the evaporation of the moisture from the milk is particularly rapid and thorough due to the mist or 08 created by ,the alternate heating and chilling of the milk as it passes downwardly in the casing I3I. A suitable vacuum pump I99 at the top of the casing serves to draw off the mist and to create a now of air in the casing counterto the general downward passage of the milk over the several main rollers I40, MI and I42.

In order that the milk may be completely removed from the several rollers I55, I40, MI and I42, there are provided doctor blades 200 carried by shafts 20I supported by the end walls I32 and I33 of the casing. Yielding and operative enbreaker mechanism, such as the breaker mechanism G shown in Fig. l, where the scrapings are broken up preparatory to being placed in containers for shipment.

Fromthe above it is seen that the dehydrating process as. performed by this modified form of theinvention includes .the steps of initially,

passing ozone through a the liquid material, forming the material as a relatively thin sheet and passing the same downwardly through alternate zones of heat and cold in a countercurrent of air to partially dehydrate the material, and supporting the partially dehydrated material in the form of a thin sheet and bubbling warm dry air up through the material to thoroughly aerate gagement between the doctor blades 2'00 and the respective rollersis maintained by spring fingers 202 (see Fig. 6) which engage in slots 203 in the ends of the doctor blade shafts.

As the partially dehydrated milk is scraped from the lower main roller I42 it drops on the drum adjacent the rear extremity of the slot I68, and as the drum rotates it forms as arelatively thin viscous sheet. While on the rotating drum I63, the warm dry air or oxygen, prefand further dehydrate the same.

Preferably," and as shown, there are provided within the casing I3I and at either side of the main rollers I40, I4I and I42 a plurality of lamps 205 for directing ultraviolet rays to the milk as it flows downwardly in the casing. These ultraviolet-ray lamps may be of any suitble construction, as: for example a mercury arc lamp.

Such irradiation of milk by ultra-violet rays has so that they may be swung outwardly to open erably having a temperature of about 100 degrees F., is bubbled or percolated through the milk. This warm dry air serves to substantially complete the dehydration of the milk and, moreover, of particular importance, the intimate intermixture of the air and the milk serves to preserve the fat globules in the milk intact during the final dehydration. The air from the drum I63 after bubbling through the milk is drawn upwardly through and out of the casing I3I by the vacuum pump I99.

As the drum I63 rotates the thoroughly aerated and substantially dehydrated scraped from the drum by the doctor blade I15 and falls to the troughlike bottom of the casing where the screw conveyer I9I, similarly to the conveyer 88 in Fig. 3, moves the milk outwardly from the casing I3I and through the housing I93. During the passage of the milk through the housing I93 it is preferably, min the form of the invention disclosed inFigs. 1 through 4, subjected to a countercurrent of warm, air to'remove any moisture that may yet remain inthe milk. Also, as in the form shown in Figs. 1 through 4, coils 204, which may receive refrigerant from the pipe I49, are arranged around the housing I93 and under the bottom of casing I3I to chill the milk and to cooperate with the warm air in further removing moisture therefrom.

Also, if desired, small lumps of carbon dioxide the'casing. Converging sectlons200 and 209 at the lower ends of 'the closure sections 206 and 201, respectively, are provided to overlap the lower sections I36 and I31, respectively, of the side walls and thus serve not only to seal the casing when the closure sections are in the p0sl-' tion shown in'Fig. 9, but serve also as stop means for limiting the swinging movement of the clocess is given for the purpose of periodically cleaning the several rollers.

In Figs. 10 and 11 there is shown another modified evaporator 2I0. This evaporator is essentially the same as the evaporator disclosed. in Figs. 5 and 9, and described immediately above. The process performed by the evaporators I30 and 2I0 is exactly the same.

The modified evaporator 2I0 differs from the evaporator I30 solely in the provision of a slightly modified main casing 21 I, and in the particular mounting of the drum from which air is permay, as in the form first described,- be added to the scrapings of substantially dehydrated milk in the bottom of the casing" I3I. This carbon dioxide sublimes, refrigerating the newly formed flakes as desired, and moreover assists in the final dehydration of the milk scrapings.

colated' through the milk.

This modified casing2II, like the casing I3I, comprises opposed end walls 2I2, opposed side walls 2I3 and 2I4" which preferably have lower sections 2J5 and 2I6, respectively, which con- Upon discharge from the housing I03 the deverge inwardly to provide a troughlike bottom for the casing I3I, and a top wall 2" which supports a milk-receiving tank I50 for directing milk downwardly to the several main rollers I40, I4 I and 142 and the calender roller I55 therein.

The casing 2I0 differs from the casing III in the provision, in addition to the hingedly mounted closure sections 206 and 201, of a supplemental movable closure section 2I8 in the inwardly converging side wall 2I6. This supplemental movable closure section 2 I8 constitutes the upper portion of the lower section 2I6 of the side wall 201 and is hingedly connected adjacent its lower edge to the end walls 2I2 by suitable hinge connections 219. Any convenient releasable means may be provided for normally maintaining the supplemental closure section 2I8 in the closed position as shown in Fig. 11. I,

With this construction ready access is not only given to the several main rollers I40, MI and I42 and the calender roller I55, but access is also given so that the drum I63 may be readily removed from the interior of the casing for repair 1 or for any other desired purpose.

In order that the drum I63 may be thus readily removed, modified end plugs 220 ,are utilized. Thus, instead of providing integral hub extensions on the end plugs 220, as in the form disclosed in Fig. 5, separate hub extensions 22I are provided which, like the integral hub extensions I18 and I19, are rotatably mounted in bearings 222 in the end walls 2I2. As shown in Fig. 10, there is provided for connecting the separate hub 22I with the end plug 220 and for directing the warm dry air or oxygen from the blower I03 to the interior of the drum, a novel connecting member 224.

This novel connecting member 224 is generally cylindrical in form and has an exteriorly threaded portion 225 engageable with threads 226 and 221 formed inbores in the hub 22I and the end plug 220, respectively. A shoulder 228 on the connecting member 224 is engageable with the hub 22I and serves to .jam the same against the end plug 220. Formed within the connecting member 224 and extending longitudinally thereof to the interior of the drum I63 is a passage 229. Warm dry air or oxygen is forced into this passage from the blower I83 through a conduit 230 having a portion 23I encircling the connecting inember 224 and overlying apertures 232 which connect the conduit with the longitudinal passage 229 in the member 224.

Removal of the connecting member 224 may be readily accomplished by grasping the knurled turning wheel 233 secured to the outer end thereof and unscrewing the connecting member from the end plug 220.

The other end of the drum may be removably supported by means of a separate hub exactly like the hub 22I and supported by a bearing in the end wall. The end plug; at the other end of the drum is of exactly thesame construction as the end plug 220, and the connecting member at the other end of the drum differs from the connecting member 224 solely in the fact that it is solid and is not formed with a longitudinal air-conducting passage.

For facilitating the removal of the drum I63 when the connecting members are withdrawn from the end plugs, there is provided a pair of supporting tracks 234, respectively connected to the inside of the opposed end walls 2I2, and extending laterally from the main casing- 2| I. Small cutouts may be formed in the supplemental closure section 2I8 to accommodate the tracks.

With this advantageous construction, therefore, when it is desired to remove the drum I63, it is'merely necessary to swing open the movable closure sections 201 and 2I0 and to swing the pivoted forward part I10 of the sealing shield I61 downwardly into an inoperative position below and between the tracks 234. Any suitable means maybe utilized to lock the pivoted part' I10 in the lower position. Then the connecting members are removed from the end plugs 220 of the drum I63 and the latter may be rolled on the tracks 234 and out of the casing.

If desired, and as-shown in Figs. 9 and 11, perforated pipes 250 may be provided for directing warm dry air to the milk as it falls from onemain roller to another. As illustrated, one of the pipes 250 is positioned between the rollers I40 and HI and another of the pipes is positioned between the rollers I4I and'I42. The air from these pipes, which preferably extend for the width of the rollersfiaids materially in the thorough and eflicient drying of the milk. A convenie t supply of warm dry air for the pipes 250 is the blower I83 which forces warm air into the drum I63.

While in the description of the invention, its adaptation to the dehydration of milk has been particularly emphasized, it is to be understood that it is not intended to so limit the invention as it is also applicable to the dehydration of other products.

Variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others.

Having thus described the invention, what I claim is:

1. In apparatus for dessicating milk, including a casing, a plurality of vertically spaced horizon. tally extending hot and cold main rollers for partially dehydrating said milk by subjecting the same to alternate zones of heat and cold as it passes downwardly in said casing, the combination of means for directing liquid milk to the upper of said rollers; and a heated calender roller cooperable with the upper of said rollers to preheat the milk and to spread the same in a tmn 2. In an apparatus for dessicating milk, the combination of a rotatable drum for receiving milk and supporting the same in the form of a thin sheet, means for. supplying air to said drum, said drum having apertures in the surface thereof for directing air to aerate and dehydrate said milk while itis supported in the form of said thin sheet thereon; sealing means for said apertures, operable to open only those apertures passing through a limited milk supporting area during the rotation of the drum; and means for removing said dehydrated and aerated milk from said drum.

3. An apparatus for desiccating material comprising a casing; means for directing the material down into said casing in the form' of a thin sheet; alternate hot and cold rollers for subjecting-said material to alternate zones of heat and cold to partially dehydrate the same as it, passes downwardly in said casing; means in the casing r vin and supporting said material-in the form of a thin sheet after it leaves said rollers; means for introducing dry air in the bottom of the casing and removing said air at the top thereof, said air passing upwardly and engaging the material while supported in the thin sheet to aerate the same and then engaging the material passing over said rollers.

' 4. An apparatus for desiccating milk comprising a casing; means for directing liquid milk down into said casing in the form of a thin sheet; al-

temate'heated and cooled rollers for subjecting said milk to alternate zones of heat and cold to partially dehydrate the same as it passes downwardly in said casing; means for receiving and supporting the milk in the form of a thin sheet after itleaves said rollers; means beneath said rollers in said casing for causing a flow of dry air in said casing and in the opposite direction to the flow of milk therein to aerate said milk while it is supported in said form or a thin sheet;

means for conveying said dehydrated milk from.

said casing; and means for passing a current of warm air in a direction counter to that of the milk as it is moved by said conveying means.

5. In an apparatus for desiccating milk, a casing having a top and a bottom with interconnected side walls connecting same, means ior directing liquid milk downwardly through said casing in the form of a thin sheet; means comprising hot and cold rollers supported at the top of the casing for supporting and dehydgating' said milk, means supported at the bottom of the cas ing for receiving and aerating said milk after passage from the top of said casing, said dehydrating and aerating mean providing successive intercommunicating zones within said casing for handling wet and partially dry milk respectively,

said aerating means including means for sup plying warm, dry fluid to the interior of saidcasing adjacent the bottom thereof, and means at the top of said casing for enabling withdrawal of said warm fluid, said dry fluid engaging the milk flowing over the rollers to aid in dehydrating the 6. In an apparatus for desiccati'ng milk, a casing having a top and a bottom with interconnected side walls connecting same, means for directing liquid milk downwardly through said casing in the form of a thin sheet; means supported at the top of the casing for receiving and dehydrating said milk, means comprising a rotary screen drum supported at the bottom of the casing for supporting and aerating said milk after passage from the top of said casing, said dehydrating and aerating means providing successive intercommunicating zones within said casing for handling wet and partially dry milk respectively, said aerating means including warm, dry fluid supply means for the interior of said drum, said fluid bubbling through the milk supported on said drum, andmeans at the top of said casing for enabling withdrawal of said warm fluid.

7, In an apparatus for desiccating milk, a casing having a top and a bottom with interconnected side walls connecting same, means for directing liquid milk downwardly through said casing in the form of a thin sheet; means comprising hot and cold rollers supported at the top of the casing for dehydrating said milk, means comprising a' rotary screen drum supported in the bottom of the casing to receive themilk from said rollers for aerating said milk after passage from the top of said casing, said dehydrating and aerating means providing successive intercommunicating zones within said casing for handling wet and partially dry milk respectively, said aerating means including warm, dry fluid supply means for the interior of said rotary screen drum, a trough at the bottom of said rotary screen drum for collecting dried aerated milk therefrom, ro-

tary means for cleaning out said trough, driving means Joumalled in said casing for rotating said rollers, drum and clean-out means, and means at the top of said casing for enabling withdrawal of said warm fluid.

8. In an apparatus for desiccating milk, a casing having a top and a bottom with interconnected side walls connecting same, means for directing liquid milk downwardly through said casing in the form of a thin sheet; means comhandling wet and partially dry milk respectively,

said aerating means including warm, dry fluid supply means associated with the drum for bubbling said warm dry fluid through the milk in aerating zone, and means at the top or said casing for enabling withdrawal of said warm fluid.

9. The invention as deflned in claim -3, wherein Y the means for receiving and supporting the material in a thin sheet comprises downwardly inclined plate means extending transversely or the casing.

10. The invention as defined in claim 3, whereinthe means for receiving and supporting the material in a thin sheet comprises a plurality of trays over which said dehydrated material travels by gravity for further dehydration and for aeration.

11. The invention as deflned in claim 3, wherein the means for receiving and supporting the material in a thin sheet comprises a perforated memberand the means for introducing air into the casing is disposed below the perforated mem--' ber whereby the air bubbles through the material supported on said member.

12. The invention as deflned in claim 3 wherein the means for receiving and supporting the material in a thin sheet comprises a rotatable drum having an apertured material-supporting surface and the means for introducing air into the casing directs the air into the interior of the drum whereby the air passes through the apertures and bubbles through the material supported thereon.

13. An apparatus for desiccating material comprising a casing;- means tor introducing the material into the casing; dehydrating means adjacent the top ofthe casing for receiving and supporting the material in a thin sheet, said dehydrating means being arranged to permit downward movement 0! the dehydrated material; a drum at the bottom of the casing having a periorated surface for receiving and supporting the thin sheet of material moving from the dehydrating means: means for introducing drying fluid into the drum; means for directingand causing the fluid to flow only through the perforations in the part of the drum upon which the thin sheet of material is supported; and means for withdrawing the fluid from the casing adjacent the top thereof to cause the fluid to flow from the bottom or the casing to the top thereof and into engagement with the material in the dehydrating means.

HARRY I. ANDRnws.

CERTIFICATE OF CORRECTION. Patent No. 2,526,512. A August 10, 1915.

' e HARRY I. ANDREWS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, sec' ond column, line 1+2, after discharge J insert the following paragraphs -The trough and the tray 57, 62, 65 and 61; may be disposed at any desired angle. If the skimmed milk coming from the lowermost roll is thoroughly dried or if. it isa stiff liquid, the trough" and traysimay be at a b.5-degree or greater angle.

The housing 90 and trough 39 of the casing 2h with the. screw 88 may be removed so that the product will drop from the doctor blade 86 for suitable distribution. As shown by dot-and-dash lines in Figs 2 through 1.1., the upper trough 57 may be provided with 'a valve plate 122 slidable on the trough and in the side wall 25; when the slide is back andavalve 125 closed, the aperture between the ends 61.05 the trough 5T andwall 26 allows thematerial to flow down into the tray 62 next below.

floweverpwhen the valve plate 122 is pushed in it -closes the gap so that the material cannot reach the tray andwhen the valve 125 is opened an evaporated skimmed milk may be passed to suitable containers from the line 1214.. Similarily, by passing cream to the trough from the valve 75 line 59 an evaporated whole milk may be passed out through the valve 123 and line 12h.

Pag 4-, s cond column, line 50', after the word. "drawa" insert '--dry--' page 5 second column, line 22, for "suitble" read suitable-; and that the .said Letters Patent should be read Wi'ththis correction therein that the 7 same may conform to the record of the case inthe Patent Office.

Signed and sealed this 16th day of November, A. o. 19Lt5.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

